CPMAS NMR spectra of Humic acids used for soil incubationHydrophobicity Index(HB)HALLignite [(0-40) + (110-160)]HB = 1.4 ArI = 25%[(40-110) + (140-190)]Aromaticity Index (Arl)Compost HAC[(110-160)]× 100HB= 1.2 ArI=5%[(0-190]2060140100180220
220 180 140 100 60 20 Lignite HAL HB = 1.4 ArI = 25% CPMAS NMR spectra of Humic acids used for soil incubation: Compost HAC HB= 1.2 ArI=5% Aromaticity Index (ArI) Hydrophobicity Index(HB) [(0–40) + (110–160)] [(40–110) + (140–190)] [(110–160)] [(0–190)] × 100
incubation experiment:dissolution13C2-ol stock360 mg of 13C2-olsolution300 ml H,0/Acetone400 ml H,0100 ml 13C2-l500 ml of 13CS13C=+2600 %ostock solutionlabelled solution A100 ml 13C2-0lstock solution500 ml of 13C600 mg HAL in 400 mls13C=+2800 %o0.01MNaOH solution (pH7)labelled solution B100 ml 13C2-0lstock solution500 ml of 13C600 mg HAC in 400 mlS13C=+2800 %o0.01MNaOH solution (pH7)labelled solution C
incubation experiment: 360 mg of 13C2-ol 300 ml H2 O/Acetone dissolution 13C2-ol stock solution 100 ml 13C2-ol stock solution 400 ml H2 O 500 ml of 13C labelled solution A δ13C=+2600 ‰ 500 ml of 13C labelled solution B δ13C=+2800 ‰ 600 mg HAL in 400 ml 0.01MNaOH solution (pH7) 100 ml 13C2-ol stock solution 600 mg HAC in 400 ml 0.01MNaOH solution (pH7) 100 ml 13C2-ol stock solution 500 ml of 13C labelled solution C δ13C=+2800 ‰
soil samples from surface horizon (O-20 cm) were collected from agriculturalsoil (FAO cl. Dystric Cambisol) air dried and sieved through a 2 mm sieve :pH (KCI)= 5.6; sand/silt/clay (%) =48/43/9; OM (%)= 3.140 ml40 ml40 ml40 mlsol. Csol. Bsol. AH,01I11150g150 g150g150g13C-HAL13C-HAC13C-2dec.controlsoil samples were incubated at constant moisture for 6 months4 replicates for each treatmentsSampling times = t0 1week; t1 12 weeks; t2 25 weeks
soil samples from surface horizon (0-20 cm) were collected from agricultural soil (FAO cl. Dystric Cambisol) air dried and sieved through a 2 mm sieve : pH (KCl)= 5.6; sand/silt/clay (%) =48/43/9; OM (%)= 3.1 150 g 40 ml H2 0 150 g 40 ml sol. A 150 g 40 ml sol. B 40 ml sol. C 150 g control control 13 C -2dec. 13 C -HAC 13 C -HAL soil samples were incubated at constant moisture for 6 months 4 replicates for each treatments Sampling times = t0 1week; t1 12 weeks; t2 25 weeks
in order to follow the distribution of labelled 13C-decanol also insoil fractions, the soil samples at each sampling date werephysically separated in particle-size fractions through theapplication of low energy sonication methodlow energy sonication (170 Jg-1) was used in order to reproduce onincubated samples the disturbing action of agricultural practices(ploughing), raindrop and drying-wetting cycles, which causenatural breakdown of soil macro-aggregates (> 250 μ)the applied low energy thus preserve the integrity of micro-aggregates (< 250 μ) thereby avoiding the artificial redistribution oforganicmatteramong soilfractionsParticle size fractions were obtained in the following rangesassociated toclassical textural classes:2000-200μmcoarse sand", 200-63 μm“fine sand", 63-2 μmsilt"<2umclay",<0.1 um“fine clay"(DOM)
in order to follow the distribution of labelled 13C-decanol also in soil fractions, the soil samples at each sampling date were physically separated in particle-size fractions through the application of low energy sonication method low energy sonication (170 Jg-1) was used in order to reproduce on incubated samples the disturbing action of agricultural practices (ploughing), raindrop and drying-wetting cycles, which cause natural breakdown of soil macro-aggregates (> 250 μ ) the applied low energy thus preserve the integrity of microaggregates (< 250 μ) thereby avoiding the artificial redistribution of organic matter among soil fractions. Particle size fractions were obtained in the following ranges associated to classical textural classes: 2000-200 μm “coarse sand ”, 200-63 μm “fine sand”, 63-2 μm “silt”, < 2 μm“clay”, < 0.1 μm “fine clay” (DOM)
most soil sample (35g d.w.) in a glass beaker with 100 ml of distilled waterultrasonication 50J s-1 120 smanual wet sieving2000-200μ coarse sand2000-63ufine sand< 63μ suspensionsupernatant=1000-1300 rpm × 5-3 min3 timespellets(resuspension)supernatantcentrifugationat 150g=7000 rpm × 20 min63-2μ siltpellets(resuspension)<0.luclaycentrifugation at 3900 gsoluble fractionDOM< 2μ clay
most soil sample (35g d.w.) in a glass beaker with 100 ml of distilled water ultrasonication 50J s-1 120 s manual wet sieving 2000-200μ coarse sand 2000-63μ fine sand < 63μ suspension supernatant centrifugation at 150 g pellets (resuspension) centrifugation at 150 g 3 times 63-2μ silt supernatant centrifugation at 3900g < 2μ clay pellets (resuspension) < 0.1μ clay soluble fraction DOM ≅1000-1300 rpm × 5-3 min ≅7000 rpm × 20 min centrifugation at 3900 g